An electric vehicle (EV) charging system may basically be defined as a system for charging a high-voltage battery mounted on an EV by using power of an energy storage device or a power grid of a commercial power source. Such the EV charging system may have various forms according to the type of EV. For example, the EV charging system may be classified into a conductive charging type using a charging cable and a non-contact wireless power transfer (WPT) type (also referred to as an ‘inductive charging type’).
In the case of inductive charging using a WPT system, when it is necessary to charge the high-voltage battery mounted on the EV, the EV may move to a ground assembly (GA) located in a charging station or a charging spot capable of EV charging.
When charging the EV, a vehicle assembly (VA) (i.e., a reception pad in the VA) mounted on the EV makes an inductive resonance coupling with a transmission pad of the GA located in the charging station or the charging spot, and charges the battery in the EV using power transferred from the GA through the inductive resonance coupling.
On the other hand, the reception pad mounted on the EV should be aligned with the transmission pad installed on the ground to improve or secure the efficiency of wireless power transfer. That is, if the alignment between the reception pad and the transmission pad is not properly performed, the wireless charging efficiency may be lowered. In the conventional wireless charging system, one or both of the pads can be moved only on the horizontal or vertical axis during pad alignment process before the power transmission. In the present reason, when the reception pad in the EV is tilted to one side, although it appears as if it is aligned on a flat surface, the height of the reception pad is not uniform on the side surface, which causes a decrease in the wireless charging efficiency.
As described above, in the wireless power transfer for the EV, since the charging efficiency greatly changes according to an error of the alignment between the transmission pad and the reception pad, precise alignment between the transmission pad and the reception pad is required even when the transmission and reception pads are tilted with respect to each other.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and may not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.